﻿#if DEF_CLIENT

using System.IO;

public class CRCComparer
{
    static uint[] Crc32Table =
    {
            0x00000000,0x77073096,0xEE0E612C,0x990951BA,
            0x076DC419,0x706AF48F,0xE963A535,0x9E6495A3,
            0x0EDB8832,0x79DCB8A4,0xE0D5E91E,0x97D2D988,
            0x09B64C2B,0x7EB17CBD,0xE7B82D07,0x90BF1D91,
            0x1DB71064,0x6AB020F2,0xF3B97148,0x84BE41DE,
            0x1ADAD47D,0x6DDDE4EB,0xF4D4B551,0x83D385C7,
            0x136C9856,0x646BA8C0,0xFD62F97A,0x8A65C9EC,
            0x14015C4F,0x63066CD9,0xFA0F3D63,0x8D080DF5,
            0x3B6E20C8,0x4C69105E,0xD56041E4,0xA2677172,
            0x3C03E4D1,0x4B04D447,0xD20D85FD,0xA50AB56B,
            0x35B5A8FA,0x42B2986C,0xDBBBC9D6,0xACBCF940,
            0x32D86CE3,0x45DF5C75,0xDCD60DCF,0xABD13D59,
            0x26D930AC,0x51DE003A,0xC8D75180,0xBFD06116,
            0x21B4F4B5,0x56B3C423,0xCFBA9599,0xB8BDA50F,
            0x2802B89E,0x5F058808,0xC60CD9B2,0xB10BE924,
            0x2F6F7C87,0x58684C11,0xC1611DAB,0xB6662D3D,
            0x76DC4190,0x01DB7106,0x98D220BC,0xEFD5102A,
            0x71B18589,0x06B6B51F,0x9FBFE4A5,0xE8B8D433,
            0x7807C9A2,0x0F00F934,0x9609A88E,0xE10E9818,
            0x7F6A0DBB,0x086D3D2D,0x91646C97,0xE6635C01,
            0x6B6B51F4,0x1C6C6162,0x856530D8,0xF262004E,
            0x6C0695ED,0x1B01A57B,0x8208F4C1,0xF50FC457,
            0x65B0D9C6,0x12B7E950,0x8BBEB8EA,0xFCB9887C,
            0x62DD1DDF,0x15DA2D49,0x8CD37CF3,0xFBD44C65,
            0x4DB26158,0x3AB551CE,0xA3BC0074,0xD4BB30E2,
            0x4ADFA541,0x3DD895D7,0xA4D1C46D,0xD3D6F4FB,
            0x4369E96A,0x346ED9FC,0xAD678846,0xDA60B8D0,
            0x44042D73,0x33031DE5,0xAA0A4C5F,0xDD0D7CC9,
            0x5005713C,0x270241AA,0xBE0B1010,0xC90C2086,
            0x5768B525,0x206F85B3,0xB966D409,0xCE61E49F,
            0x5EDEF90E,0x29D9C998,0xB0D09822,0xC7D7A8B4,
            0x59B33D17,0x2EB40D81,0xB7BD5C3B,0xC0BA6CAD,
            0xEDB88320,0x9ABFB3B6,0x03B6E20C,0x74B1D29A,
            0xEAD54739,0x9DD277AF,0x04DB2615,0x73DC1683,
            0xE3630B12,0x94643B84,0x0D6D6A3E,0x7A6A5AA8,
            0xE40ECF0B,0x9309FF9D,0x0A00AE27,0x7D079EB1,
            0xF00F9344,0x8708A3D2,0x1E01F268,0x6906C2FE,
            0xF762575D,0x806567CB,0x196C3671,0x6E6B06E7,
            0xFED41B76,0x89D32BE0,0x10DA7A5A,0x67DD4ACC,
            0xF9B9DF6F,0x8EBEEFF9,0x17B7BE43,0x60B08ED5,
            0xD6D6A3E8,0xA1D1937E,0x38D8C2C4,0x4FDFF252,
            0xD1BB67F1,0xA6BC5767,0x3FB506DD,0x48B2364B,
            0xD80D2BDA,0xAF0A1B4C,0x36034AF6,0x41047A60,
            0xDF60EFC3,0xA867DF55,0x316E8EEF,0x4669BE79,
            0xCB61B38C,0xBC66831A,0x256FD2A0,0x5268E236,
            0xCC0C7795,0xBB0B4703,0x220216B9,0x5505262F,
            0xC5BA3BBE,0xB2BD0B28,0x2BB45A92,0x5CB36A04,
            0xC2D7FFA7,0xB5D0CF31,0x2CD99E8B,0x5BDEAE1D,
            0x9B64C2B0,0xEC63F226,0x756AA39C,0x026D930A,
            0x9C0906A9,0xEB0E363F,0x72076785,0x05005713,
            0x95BF4A82,0xE2B87A14,0x7BB12BAE,0x0CB61B38,
            0x92D28E9B,0xE5D5BE0D,0x7CDCEFB7,0x0BDBDF21,
            0x86D3D2D4,0xF1D4E242,0x68DDB3F8,0x1FDA836E,
            0x81BE16CD,0xF6B9265B,0x6FB077E1,0x18B74777,
            0x88085AE6,0xFF0F6A70,0x66063BCA,0x11010B5C,
            0x8F659EFF,0xF862AE69,0x616BFFD3,0x166CCF45,
            0xA00AE278,0xD70DD2EE,0x4E048354,0x3903B3C2,
            0xA7672661,0xD06016F7,0x4969474D,0x3E6E77DB,
            0xAED16A4A,0xD9D65ADC,0x40DF0B66,0x37D83BF0,
            0xA9BCAE53,0xDEBB9EC5,0x47B2CF7F,0x30B5FFE9,
            0xBDBDF21C,0xCABAC28A,0x53B39330,0x24B4A3A6,
            0xBAD03605,0xCDD70693,0x54DE5729,0x23D967BF,
            0xB3667A2E,0xC4614AB8,0x5D681B02,0x2A6F2B94,
            0xB40BBE37,0xC30C8EA1,0x5A05DF1B,0x2D02EF8D
    };

    public static uint GetCRC32(byte[] bytes)
    {
        uint iCount = (uint)bytes.Length;
        uint crc = 0xFFFFFFFF;

        for (uint i = 0; i < iCount; i++)
        {
            crc = (crc << 8) ^ Crc32Table[(crc >> 24) ^ bytes[i]];
        }
        return crc;
    }

    // 获取文件的CRC32标识
    public static string GetFileCRC32(string filePath)
    {
        if (string.IsNullOrEmpty(filePath))
        {
            return string.Empty;
        }

        if (!File.Exists(filePath))
        {
            return string.Empty;
        }

        // 最大50M
        const int MAX_SIZE = 50 * 1024 * 1024;
        var f = new FileInfo(filePath);
        if (f.Length >= MAX_SIZE)
        {
            return string.Empty;
        }

        uint crc = 0xFFFFFFFF;
        var bin = File.ReadAllBytes(filePath);
        foreach (byte b in bin)
        {
            crc = ((crc >> 8) & 0x00FFFFFF) ^ Crc32Table[(crc ^ b) & 0xFF];
        }
        crc = crc ^ 0xFFFFFFFF;
        return crc.ToString("X");
    }

    //---------------------------------------------------------------------
    public static bool IsSameFile(string local_filepath, string remote_filemd5)
    {
        string crc = GetFileCRC32(local_filepath);
        bool is_same = crc.Equals(remote_filemd5);
        return is_same;
    }

    //---------------------------------------------------------------------
    public static string GetFileCRC(string local_filepath)
    {
        return GetFileCRC32(local_filepath);
    }
}

#endif